ever changing earth

• Crust


  The outer part of the Earth
• Magma


  Floating on molten rock
• Mag te rock
• Plate tectonics


  The theory that the Earth's crust is broken up into about 8 major parts called plates that are moving due to convection currents in the magma
• Convection current


  The movement of heat in a liquid or gas
• Continental drift


  The theory that the continents were originally joined together in one land mass called Pangea and have slowly moved apart
• Evidence for continental drift

  • The east coast of South America and the west coast of Africa appeared to fit together like a jigsaw
  • The rocks on these coastlines were the same
  • The fossils the rock contained were the same
• Wegener's idea of continental drift was not accepted because he couldn't explain why the continents moved
• It was only in the 1960s (20-30 years after Alfred died) when scientists were studying the bottom of the Atlantic Ocean, did they realise the sea floor was "spreading" (plates moving apart)
• Rocks were dated using radioactive isotopes
• Plate boundary


  1. Plates move apart

  2. Plates move together

  3. Plates have different densities, the plate with the higher density will sink into the magma and melt

  4. Plates have the same density the crust is deformed
• Constructive plate boundary


  • Happens along the mid-Atlantic ridge (plate boundary) which runs through the middle of the ocean
  • Earthquakes and volcanoes happen here
• Destructive plate boundary


  • Rock is being destroyed
  • Earthquakes and volcanoes happen here
• Conservative plate boundary


  • Plates slide past each other
  • Earthquakes happen here
• If you look at where earthquakes and volcanoes occur, you will be able to see the pattern of the plate boundaries
• Formation of the atmosphere

  1. As the Earth cooled down the water vapour in the atmosphere condensed

  2. The carbon dioxide in the atmosphere decreased due to development of photosynthesising plants

  3. Oxygen gas and carbon dioxide gas then reacted together to produce nitrogen gas
• Composition of today's atmosphere

  • Nitrogen: 78%
  • Oxygen: 22%
  • Argon: 0.9%
  • Carbon dioxide: 0.04%
  • Other gases: 0.06%
• Photosynthesis was the main reason for the decrease in carbon dioxide in the atmosphere
• Carbon cycle


  The amount of oxygen and carbon dioxide in today's atmosphere are controlled by the carbon cycle
• Carbon cycle


  1. Photosynthesis

  2. Respiration

  3. Combustion
• Due to the increase in both burning of fossil fuels and deforestation

  The amount of carbon dioxide in the atmosphere is increasing
• Increased carbon dioxide in the atmosphere

  Stops heat escaping from the atmosphere, which means the temperature of the Earth's atmosphere will increase (global warming)
• Global warming causes ice caps to melt faster, climate change, and sea level rise
• Ways to reduce global warming

  • Use more renewable energy instead of fossil fuels
  • Carbon capture and storage
  • Reduce combustion of fossil fuels
• Acid rain


  Caused by sulfur dioxide gas produced when fossil fuels containing sulfur are burnt
• Acid rain can damage plants, kill fish, and corrode metal and rocks
• Ways to reduce acid rain

  • Use fossil fuels with less sulfur
  • Carry out "sulfur scrubbing" to neutralise the sulfur dioxide
• Carbon neutral fuels like wood simply replace the carbon dioxide produced during combustion with the carbon dioxide absorbed during photosynthesis